1 Gyrodactylus salaris Taxon Family / Order / Class / Phylum Gyrodactylus salaris Malmberg, 1957 Gyrodactylidae / Monopisthocotylea / Turbellaria /. Platyhelminthes COMMON NAMES (English only). Salmon fluke SYNONYMS. None. SHORT DESCRIPTION. This is a very small worm parasite (<1mm) which attaches to the outer body and gills of fish in the salmon family. It damages the skin and this can lead to infections. Unless heavily infested, it is unlikely that its presence will be noticed. There are many related Gyrodactylus species that are difficult to distinguish. This genus contains specialist and generalist parasites. BIOLOGY/ECOLOGY. Dispersal mechanisms Associated with fish movements of Atlantic salmon and rainbow trout in fresh and brackish water. May be spread to different catchments by piscivorous birds. Reproduction Individuals are small, ~ long, and Gyrodactylus salaris females have up to four viviparous broods of 2-7 Photo: Kurt Buchmann individuals, the first may be asexually produced.
2 Populations rapidly develop at C, but can also grow at C (surviving 33 days) to 19 C ( days). It may reproduce on different salmonids. Known predators/herbivores Unknown. Resistant stages (seeds, spores etc.). None. HABITAT. Native (EUNIS code). Ectoparasitie: on the surfaces of Atlantic salmon Salmo salar. Habitat occupied in invaded range (EUNIS code). Ectoparasite: on the skin, gills and fins, heavy infections normally occur on the body and caudal fin. Habitat requirements It is a cold water species surviving at temperatures 0-20 C and salinities up to 7psu. At higher salinity reproductive capability and longevity declines. DISTRIBUTION. Native range Adapted to an isolated evolutionary form of Atlantic salmon in Baltic river catchments in Russia, Sweden, Finland, Latvia and Lithuania. Known Introduced Range Norway, Finland and White Sea region of Russia, Denmark (on farmed rainbow trout).
3 Trend Restricted range but this may expand. MAP (European distribution). Legend Known in country Known in CGRS square Known in sea Native in country Native in CGRS square Assumed native range INTRODUCTION PATHWAY. Aquaculture and stocking. Movements of infected salmon or rainbow trout fingerlings and perhaps with fish-farm, fishing and water sports equipment. Can survive in air under damp conditions for some days. Movement of hosts to different catchments where there is freshwater to brackish water. IMPACT. Ecosystem Impact It results in a significant mortality of young salmon in river catchments outside of the northern Baltic Sea, in Norway, northern Finland and the White Sea area. Reports from Portugal, Spain, France and Germany may be misidentifications. May cause reduced unionid recruitment caused by declines in abundance of salmonids. Health and Social Impact High mortalities of salmon outside of its native range, but no human effects.
4 Economic Impact In Norway, estimates of annual losses in production in the late 1990's from salmon farms was 250-500 tonnes of production. MANAGEMENT. Prevention Stock transfers of fish from risk areas to uninfested areas should not take place. Mechanical Restrictions on imports. Chemical Eradication using rotenone has been effective in eliminating its presence in 16 Norwegian waterbodies. Aqueous aluminium may be effective for treating fish for stocking. Detached trematodes are able to infect free-swimming salmon although they have no swimming ability themselves. The use of brackish treatments needs to be reviewed. Populations have declined arising from control measures in Norway. Biological Unknown. REFERENCES. Appleby C, Mo TA (1997) Population dynamics of Gyrodactylus salaris (Monogenea) infecting Atlantic salmon, Salmo salar, parr in the river Batnfjordselva, Norway.
5 Parasit 83(1):23-30. Harris PD, Jansen PA, Bakke TA (1994) The population age structure and reproductive biology of Gyrodactylus salaris Malmberg (Monogenea). Parasit 108:167-173. Johnsen BO, Jensen AJ (1986) The Gyrodactylus story in Norway. Aquaculture 98:289-302. OTHER REFERENCES. Bakke TA, Jansen PA, Hansen LP (1990) Differences in the host resistance of Atlantic salmon, Salmo salar L. stocks to the monogenean Gyrodactylus salaris Malmberg, 1957. J Fish Biol 37:577-587. Bakke TA, Harris PD, Hansen H, Cable J, Hansen LP (2004) Susceptibility of Baltic and East Atlantic salmon Salmo salar stocks to Gyrodactylus salaris (Monogenea). Dis Aquat Org 58 (2-3):171-177. Buchmann K, Bresciani J (1997) Parasitic infections in pond-reared rainbow trout Oncorhynchus mykiss in Denmark. Dis Aquat Org 28:125-138. Malmberg, 1957 (Platyhelminthes: Monogenea) on Atlantic salmon (Salmo salar L.)
6 Parasit 102 (1): 105-112. Mo TA (1994) Status of Gyrodactylus salaris problems and research in Norway. In: Pike & Lewis (eds). Parasitic diseases of fish Samara Publishing Ltd.,Otley, Yorkshire pp 43-56. Nielsen CV, Buchmann K (2001) Occurrence of Gyrodactylus parasites in Danish fish farms. Bull Eur Ass Fish Path 21(1):19-25. Soleng A, Bakke TA (1997) Salinity tolerance of Gyrodactylus salaris (Platyhelminthes, Monogenea): laboratory studies. Can J Fish Aquat Sci 54:1837-1845. Author: Dan Minchin Date Last Modified: January 7th, 2008.